For lighter plows such as are typically mounted to pick-up trucks, a variety of attachment systems have been developed that can be employed to mount a plow assembly. Two such patents teach a mounting for a plow that clamps onto a vehicle-mounted frame using upper and lower hooks in combination with guiding elements; these are U.S. Pat. Nos. 7,114,270 and 7,353,628. These patents share a common disclosure and teach a mount having a grasping mechanism which is guided into position as it closes by engagement of the upper hooks with an angled section of the vehicle-mounted frame and by engagement of angled surfaces on the lower hooks with corresponding surfaces on the vehicle-mounted frame, these surfaces both centering the grasping mechanism and guiding a lower bar of the vehicle-mounted frame into a trapped position. U.S. Pat. No. 4,236,329, which was cited during prosecution of these '270 patent, teaches a mount having opposed upper and lower hooks at a fixed separation that are engaged by parallel bars on the vehicle when these bars are moved to a maximum separation into engagement with the hooks. All of these mounts are designed for lighter plows. One of the benefits of the systems taught in the '270 and '628 patents is that, when the clamps are aligned with the bars (the truck is normal to the plow assembly) and the bars positioned therebetween (the truck is in close proximity to the plow), the engagement of the clamps with the bars will result in centering the plow with respect to truck.
For heavier duty plows, and particularly for plows having side wing attachments, a variety attachment systems have been developed. One such coupling device is taught in U.S. Pat. No. 4,744,159. One limitation of this system is that the drive actuators of the attachment mechanism reside on the vehicle even when the plow is detached. However, this patent again teaches a system where, if the plow coupling assembly is substantially aligned with the front of the truck and in close proximity thereto, the structure will center the plow with respect to the truck.